docs: def published_children(self):
          """Return a :class:`QuerySet` of published children page"""
          key = self.PUB_CHILDREN_KEY % self.pk
          #children = cache.get(key, None)
          # if children is None:
          children = Page.objects.filter_published(self.get_children()).all()
          #cache.set(key, children)
          return children